Question: Emily has breakfast at a restaurant and the cost of her meal is $\$40.00$. She would like to leave a $20\%$ tip. What is her total bill including tip?
Solution: The tip amount is equal to $20\% \times \$40.00$ We can find the tip by first calculating a $10\%$ tip and then multiplying that number by two. To calculate a $10\%$ tip, move the decimal point in $\$40.00$ one place to the left. $10\%$ $\times \$40.00$ $\$4.00$ To calculate a $20\%$ tip, multiply the $10\%$ tip amount by two. $20\%$ $\times \$40.00$ $\$4.00$ $ \times 2 = $ $\$8.00$ The cost of the meal plus the amount of the tip will equal the total bill amount. $\$40.00 + \$8.00 = $ $\$48.00$ The total cost of the bill is $\$48.00$.